Apparatus for lubricating plastic materials undergoing extrusion



20, 1952 D. J. WEBER 2,597,553

APPARATUS FOR LUBRICATING PLASTIC MATERIALS UNDERGOING EXTRUSION FiiedSept. 17, 1948 v 2 SHEETS-SHEET 1 26, 1952 D- J. WEBER 2,597,553

APPARATUS FOR LUBRICATING PLASTIC MATERIALS UNDERGOING EXTRUSION FiledSept. 17, 1948 2 SHEETS--Sl-1EET 2 flozzairi J fier "aii'ornej PatentedMay 20, 1952 NHTED STATES PATENT OFFICE .APPARATUSFOBLUBRICATIN GPLASTIC .MATERIALS UNDERGOING 'EXTRUSI ON 7 Claims. 1

This invention relates to apparatus for extruding plastic materials toproduce elongated bodies possessing uniform cross-sectionalcharacteristics throughout their lengths. Among. such bodies may bementioned rods, tubes, strips and sheets.

In the extrusion of plastics to-form such bodies, the plastic compoundsare heated to reduce the same to a flowable molten state so that the,same may be advanced under pressure through the orifice or orifices of aforming die or head in which the desired cross-sectional shape isimparted to the moving plastic mass, the latter being then cooled tocause the same to solidify and assume desired final formations. In suchextrusion machines, considerable difiicnlty has been encountered in thematter of -maintaining the desired movement of the plastics while thesame are passing through the shape-imparting openings or barrels of theforming head or die.

Plastic materials when so heated become sticky or tacky and the sametend to jam or unduly adhere to the passage walls of the forming head ordie and this condition often results in the formation of products whichare defective from a standpoint of utilization in that theymay containvoids, cracks or other imperfect-ions.

In order to provide for the desiredflow of the plastics through such aforming die, it has been the practice in the prior artto introduce alubricant in limited quantities and under high pressures 'into theforming passages so that -.a film of lubricant may be providedbetweentheplastics moving through such passages and'the wall surfaces of thepassages. Such a system of introducing a lubricant directly into thepassages of the forming die or head is difiicultto control byconventional valves and pressure forces on the lubricant, oftenresulting in an excess supply of the lubricant or a too restricted flow.

It is an object, therefore, of thepresent invention to provide theforming die or head-structure of a plastic extruding machine with achamber formed for the reception of a metallic oil ring and whereinprovision is made for forcing a lubricant under pressure through themicroscopic pores or interstitial channels of the-ring to depositcontinuously a film of the lubricant on the inner surfaces of the ring,whereby to facilitate the travel of plastic compositions undergoingshaping formation.

It is another object of the'invention to provide a lubricating ring forthe heads of plastic extruding machines in which the wa-ll thickness ofthe ring varies throughout itslength, the ri-ng closed as being situatedin a vertical plane.

possessing its minimum thickness at the end thereof receiving theplastic materials undergoing extrusionand the opposite or plasticdischarge end of the ring possessing its maximum Wall thickness, thearrangement being such as to provide for the highest rate of oildelivery to the plastics when they enter the ring and to diminishgradually the supply of lubricant to the ring at the plastics dischargeend thereof.

For a further understanding of the invention, reference is to be had tothe following description and the accompanying drawings, wherein:

Fig. 1 is a vertical sectional view taken partially through the screwstuifer of a plastics extruding machine and disclosing in associationtherewiththe head or die of such a machine, the cooled forming barrelthereof and the lubricating ring or collar comprising the presentinvention. In this figure, the extrusion apparatus is adapted for theformation of rods or the like.

Fig. 2 is a side elevational view of the apparatus disclosed in Fig. 1;

Fig. 3 is a vertical sectional view similar to Fig. 1 "but showing thehead or die constructed for the extrusion of tubes and other similarhollow bodies. In this figure concentrically arrangedinner and outerlubricating ringsare disclosed as mounted in the head or die of themachine;

Fig. 4 is a transverse vertical sectional view taken on the line 4-4 ofFig. 3;

Fig. 5 isa vertical sectional view taken through the forming head of anextrusion machine and wherein the head isformed to eifect the formationof tubular bodies with the aid of internally pneumatic pressures;

Fig. Bis a transverse sectional view disclosing the ported spider ringof the extrusion head;

Fig. 'lis a vertical sectional view taken through another form ofextrusion head employing my presentinvention in which the head isadapted for the formation of articlespossess-ing an irregularcross-sectional configuration;

Figs. 8, 9'andl0 are detail transverse sectional views taken on thelines 8-8, 9-4] and I0l0 of-Fig. 7.

Referring more particularly to the drawings, the numerall designates thecasing of an extrusion machine, which in this instance is dis- Thecasing is formed with the usual internal chamber 2 on which is mounted arotatable stufier screw 3 "by which plastic material in a heated ormolten state isadvanced to the extrusion head .or die Act the machine.The casing I is provided with a bottom plate 5 having a substantiallyconical pocket 6 formed therein for receiving the plastic from thechamber 2, the pocket 6 terminating in a reduced passage 1 whichcommunicates with the vertical leg 8 formed in the head or die 4. .Atits lower end, the leg 8 terminates in a horizontally extending portion9. The portion 9 is disposed for registration with an outwardly flaringport l provided with an inner head plate H. Cooperative with the plateII is an intermediate plate l2 and an outer plate l3, the plates ll, l2and 13 being formed with registering openings through which headedscrews l pass for securing the plates to the head or die 4. These platesmay be provided with interengaging shoulders 16 to preserve theiralignment.

The intermediate plate is formed with an axially arranged chamber I! inwhich is provided an oiling ring or collar I8, which forms an essentialfeature in the present invention. This ring is of metallic compositionand is pref.. erably composed of bronze, although the same may be formedfrom other metals such as brass, stainless steel, Monel metal or anyother suitable material having rigidity and sufficient porosity topermit of the passage therethrough of a lubricating oil under pressure,the oil or other lubricant passing through the pores or interstitialpassages or crevices of the material comprising the ring so that it willbe delivered to the wall surfaces of the internal opening I9 of the ringwhich is disposed in registration with the larger end of the port l0provided in the head plate I I.

Preferably, the diameter of the opening I9, which is uniform throughoutthe length of the opening, is very slightly greater than that of thelarger end of the port I0, whereby to facilitate the flow of the heatedplastics and to enable the same to pick up the oil sweated on the wallsurfaces of the opening I 9.

Another important feature of th invention resides in the cross-sectionalconfiguration of the ring l8. By reference to Fig. 1, it will be notedthat the ring generally is of frusto-conical configuration, having anannular concave outer wall 20 which causes the ring to possess itsminimum wall thickness at its plastics-receiving end and its maximumwall thickness at its plastics-discharge end. By this construction, thechamber ll provides an oil-containing well around the ring. As a resultof the reduced wall thickness at its plastics-receiving end, a largeramount of oil penetrates the ring at the forward or plastics-receivingend thereof, where the larger quantity of oil is needed to insure thesustained and uninterrupted flow of the plastics without allowing thelatter to seize or bind on the walls of the aligned forming passages. Asthe plastics progress through the opening I9 of the ring, the amount ofoil supplied thereto is gradually diminished by the increasing wallthickness of the ring. This formation of the ring is of criticalimportance in a continuous operation of extruding shaped bodies ofplastics, as distinguished from an intermittent operation such as thatproduced by a reciprocating plunger for effecting the advancement ofheated plastics through an extruding die. If the wall thickness of thering were uniform in a continuous operation such as that here disclosed,the oil accumulations on the inner wall surface of the ring will befound to have a tendency to pocket and disfigure the outer surfaces ofthe formed plastic bodies. However, this'objection is entirelyeliminated with the em- 4 ployment of a ring having the progressivelyincreasing wall thickness here disclosed.

Lubricating oil may be delivered to the chamber I! around the ring l8 bythe operation of a motor driven pump 2|, the outlet line 22 of whichleads from the pressure side of the pump to an accumulator tank 23 inwhich the oil is maintained under a constant predetermined workingtemperature. A spring-loaded return valve 24 is arranged in a pipe line25 to return excess oil to the inlet side of the pump when a desiredpressure is reached in the tank 23. Leading from the tank 23 is a pipeline 26 having therein a manually operated control valve 21. The pipeline 26 extends to a passage 28 provided in the intermediate plate I 2and which leads to the chamber H.

The outer head plate I3 is provided with a longitudinally extendingbarrel 29 of any suitable length. This barrel is arranged inregistration and communication with the opening l9 in the ring [8 andpossesses the same internal diameter as said opening. Surrounding thebarrel 23 is a jacket 30, the walls of the latter being spaced from theouter walls of the barrel to provide a chamber for circulation of wateror other coolant for facilitating the solidification and hardening ofthe formed plastic body, which in the apparatus shown in Fig. 1,comprises a cylindrical rod. When a formed rod is removed from thedischarge end of the barrel 29, the sam may be cut transversely intosuitable lengths and any excess oil present on the outer surfacesthereof removed by a wiping operation. The outer surfaces of the rod arecharacterized by their smooth finish and surface regularity.

In the apparatus illustrated in Figs. 3 and 4, provision is made for theextrusion of hollow bodies, such as sleeves, pipes or the like, and moreparticularly to sleeves and pipes of larger diameters than thoseheretofore made in the extrusion of plastics, that is, pipes or tubeshaving an outside diameter of two inches or greater. In this form of myinvention, the extrusion die comprises head plates indicated at 30 and3| and which are bolted or otherwise secured together. The head plate isprovided with a horizontal bore 32 and a vertically disposed passage 33.Through this passage, the heated plastics are forced by a packer screw,such as that shown at 3 in Fig. 1, the plastics being under atemperature of the order of from 275 F. to 550 F.

Positioned in the bore 32 is a core 34 having a flanged end 35 forengagement with an outer surface of the head plate 30. The core isformed with an axial opening 36 in which is positioned the reducedtubular extension 31 of a longitudinally and horizontally extendingstationary mandrel 38. The extension 31 and the body of the mandrel 38are formed with an axial passage 39 for the reception of a coolant pipe40. A coolant is introduced into this pipe at one end thereof and isdischarged at its opposite end from the pipe into the passage 39. In thepassage 39, the coolant flows in the direction opposite to that whichtakes place in the pipe 40, and is discharged from the outer end of theextension 31. The extension 31 terminates inwardly in an integral boss Mwhich possesses a greater diameter than said extension but a smallerdiameter than that of the body of the mandrel 38. This constructionprovides an annular recess 42 in which is positioned an inner oilingring 43. This ring corresponds in its cross-sectional configuration withthe ring l8 of Fig. 1. The outer peripheral surface of the ring 13 isdisposed in registration with the corresponding surf-face of the mandrel33 and in spaced concentric relation to the annular inner surface-ofa-complemental outer oiling ring 64, the latter being stationarilymounted and suitably retained in an annular recess provided in a headplate 46. This plate is mounted adjacent to the outer surface of anadjustable plate 46a, the latter being disposed in a recess 47 providedin the outer side of the head plate 3|. The plate 46a is formed with anaxial opening d8 which registers with similar openings 59 and 50provided in the plates 30 and 3|, the opening '69 communicating at oneend with the passage 33. x

The head plate tea is adjustable in the recess 41 by the provision of apluralityof radially disposed screws 5! which are carriedby theperiphery of the plate 3|. Byadjusting the screws 5!, the axial opening48 in th'ehead plate 45a may be brought into desired registration Withthe openings 59 and 59 and with the annular space 52 formed between theinner and outer oiling rings 43 and A l. The plate '46 is joined with anoutercap plate 53 which is carried'by'the inner end of a stationary tube54 which surrounds and is spaced from the mandrel 38, providing acircular forming chamber through which the plastics are advanced afterbeing lubricated on both inner and outer surfaces by the oiling rings 43and 4d.

The plate 36 is formed with a restricted passage 55 which communicateswith a pipe line 56 through which a lubricant is advanced under pressurefor the purpose of forcing the lubricant through the outer ring '44 andon to the surfaces of the plastic materials flowing through the diehead. To lubricate the inner ring 43, the core 35 is provided with asimilar restrictedpassage 5?, which leads to the recess 42, the outerend of the passage 51'commu'nicating with the pipe line 58 leading toasource of lubricant supply under pressure.

The tube 5 1 is provided with a water circulating jacket, not shown,corresponding to the jacket 30 of Fig. 1. The extension "31 isexteriorly threaded as at'59for the reception of'a clamping nut Gil, thelatter engagingthe beaded end 35 of the core 3 3. By this arrangement,tubular plastic products'may be extruded having a uniform density andwith smooth regular inner and outer wall surfaces. The apparatusparticularly lends itself to the production of tubes of larger diametersthan those heretofore produced by apparatus of this character, theproduction of such tubes being made possible-by the inner and outeroiling rings 43 and M and their cross-sectional configuration.

While the rings provide for a controlled application of an oil film-toinner and outer surfaces of the plastic materialsundergoing'formation,they specifically prevent the accumulation of pockets of oil,-as"sooften occurs in prior extruding machines of the continuously operatingtype. If the oil should so pocket and not become uniformly distributedin the form of a thin film over the'surfaces of'the'plastic materials,the latter tend to jam in the'small passages of the die head and produceimperfectly shaped ware. The proper distribution of the oil isaccomplished as a result of the arrangement in cross-sectionalconfiguration of the oiling rings of the present apparatus.

The inner walls ofthe'tubular extension '31 of the mandrel may beprovided-with a sleeve 6! composed of a thermal insulation to minimizeheat transference between the coolant-and. the heated core section'34ofthe mandrel. a

In the apparatus illustrated in Figs. '5;an'd 6, extrusion means for theformation of tubes or pipes of plastic composition has been-illustrated.This apparatus involves a simplified design somewhat less costly toproduce than the apparatus of Fig. 3, the apparatus ofFig. 5 beingparticularly useful in the manufacture of tubes or pipes of diameterssmaller than those produced by the apparatus of Fig. '3 as, for example,pipes or tubes having an outside diameter of two inches or less. i H vThe apparatus of Fig. 5 involves a stationary die head 62, having one ofits sides formed with a recess 63 whieh includes *anaxially'disposedchamber 54. Positioned in this chamber is a flange 65 formed at one endof a nozzle section 85, the flange 65 being providedwith a multiplicityof circularly arranged ports '61, The nozzlesection includes anaxial-passage 68. -At one end the passage 158 communicates with a pipe69 by means of which air under pressure is admitted into the nozzle. Atthe end of the passage 68 opposite to the pipe, there isprovided athreaded socket for the reception of a threaded nipple 19 provided on asecond nozzle section II, the latter-being formed with an axial passage12 communicating with the passage 68. The die head 62 is provided withanopening '13 for the passage of heated plastic materials, the latterbeing forced through the openings T3 in a continuous'mannerby a :packeror stuffer screw, not shown, -similar to;the screw 3.

Positioned in the recess 63 of the die headis :a block M having an axialopening 15 which constitutes a continuation of the opening 13 and thehead 62 and the ports'fil of the flange 65 for the sustained advance ofthe heated plastic materials through the die structure and aroundthenozzle sections. The walls of the openings =15 possess greaterangularity than the outer walls of the nozzle section "H sp that asmooth-restricted throat is produced around the nozzle section 11' forthe flow of the plastic materials. The block 'i' l is provided with anannularly shouldered region '16 which engages with a retaining ringII-holding the block in. its operative'position and against longitudinaldisplacement. 'Ihe'block 'is' also exteriorly threaded as at 18 for thereception of a collar 19'. This collar engages with the flanged end of athimble 3i holding the 'end 80 in contact with one ofthe wall surfacesof the block 14.

Within the thimble, there is positioned an oil ring 8201" the generaltype previously described, except that in this instance, the ring isformed with a positioning flange 33 at one endthe'reo f. In general, thebody of the ring'82 possesses the gradually increasing wall thicknesswhich is characteristic of the oil rings employed by the presentinvention. Within the "thimble, there, is provided a well aroun'dthe'oil ringwhichis supplied withoil under'pre'ssure byway of the pipeline illustrated at '84. The ring is formed with a longitudinalboreBBwhich communicates at one end with the opening and at its opposite endwith an opening. provided ina stationary barrel 8'8. Thisbarrelisthreaded'at one end as at 81 into the closed end of the thimble'8l ormay be welded thereto as desired. Surroundi'ng the barrel is ajacket 88 forthe reception of a circulating coolant. In the operation 'ofthe apparatus of Fig. 5, thehejdte'd plastic material flows through theopening 13, the port 61 and the opening 15 where it merges into the bore85 of the oil ring 82.

Simultaneously, air under pressure is delivered into the bore 85 by wayof the passages 68 and 12. The air pressure maintains the heated plasticmaterials in engagement with the walls of the bore85 and the barrel 86so that the desired tubular form of the resinous material is producedand maintained until the heated plastic materials cool and become set orhardened. Lubricant is applied through the porous oil ring as previouslydescribed, so that continuous operation may be maintained with theformed products having a smooth outer wall finish.

The apparatus illustrated in Figs. 7 to inclusive disclosesan adaptationof the present invention to the extrusion of strips or bars having anirregular transverse configuration. An I- shaped section, for example,such as that illustrated in Figs. 8 through 10 is diflicult, if notimpossible, to produce on extrusion machines and having conventionallubricating means. However, with oil rings having the progressivelyincreasing wall thicknesses, such extrusions are entirely possible andpracticable.

In Fig. '7, the die head comprises a plurality of blocks indicated at89, 9|] and 9|, these blocks being suitably joined together in assembledrelation by bolts, screws or other conventional fastening means. Theblock 89 is provided with a passage 92 for the flow of the heatedplastic materials under the action of an extrusion screw or auger of thetype indicated at 3 in Fig. 1. At its lower end, the passage 92 includesa horizontally directed section 93, the latter communicating with thesmaller end of an outwardly flaring but progressively flattened opening94 which is formed in the block 90. The block 91 is provided with achamber 95 for the reception of an oil ring 96.

This ring is of the same general type as that described in the previousforms of my invention, with the exception that the axial opening 91therein is of a shape conforming to the irregular shape of the plasticarticle undergoing formation. In this instance, the opening 91 issubstantially I-shaped in transverse formation, although it will beunderstood that this configuration is merely illustrative and is subjectto wide variation. As shown in Fig. 9, the walls of the opening 91 mayalso possess a varying thickness to concentrate oil on a given part ofthe inner surface area of said walls. The wall thicknesses of the oilring progressively increase in the direction of travel of the plasticmaterials to provide for the controlled inflow of oil into the ring. Byreason of its cross-sectional configuration, the ring produces the oilchamber 95 which is supplied with oil under pressure through the pipeconnection 98. Strips of irregular transverse configuration are thusproduced by my present apparatus which are characterized by theiruniform density, cross-sectional thickness and smooth external wallsurfaces. In all forms of my invention, continuous extrusion is madepossible over prolonged periods of operation without encountering thedifiiculties which are attributable to improper lubrication.

It will be understood that other constructions may be employed withoutdeparting from the scope of the present invention since, in thisapplication, I have merely illustrated and described several specificforms of the apparatus for the extrusion of'difierent types of plasticproducts.

8 I Also, while my apparatus is adapted for the extrusion of varioustypes of synthetic resins or organic plastics, it is entirely possibleto apply the same to the extrusion of other products whether organic orinorganic and I contemplate herein all such uses of my invention.

I claim:

1. Apparatus for extruding organic plastic materials, comprising a diehead having a forming orifice through which plastics in a heatedformative state are advanced under positive flow conditions, said headbeing formed with a chamber, a lubricating ring positioned in saidchamber, said ring having an inner wall of uniform diameter throughoutits length, said wall defining an opening forming a part of saidorifice, the outer wall surfaces of said ring possessing a taperedformation which in association with the inner wall surfaces define aring body progressively increasing in cross-sectional thickness from oneside thereof to the other, said body being formed from a material havinga porosity admitting of the passage of a lubricant therethrough underpressure, and means for introducing a lubricant under pressure into saidhead chamber for passage through said ring in which the greatest amountof the lubricant passes through that portion of the ring having reducedbody thickness and through which portion the plastic material initiallypasses upon entering the ring and a relatively reduced amount of thelubricant through that portion of the ring possessing maximum bodythickness and from which thicker portion, the plastic material travelsimmediately prior to being discharged from the ring.

2. In apparatus for extruding organic plastic materials in formedshapes, a die head having a chamber, a lubricating ring positioned insaid chamber, said ring being formed from a metal sufiiciently porous inits composition as to provide for the direct passage therethrough of alubricant under pressure, said ring having a body progressivelyincreasing in cross-sectional thickness from one side of the ring to itsother to vary the volume of lubricant penetrating said ring so that thegreatest amount of lubricant enters an axial bore of the ring adjacentto the plastic-receiving end of said bore and the least amount oflubricant at the plastic-discharging end of the ring bore.

3. In apparatus for extruding organic plastic materials in formedshapes, comprising a die head having a forming orifice through whichplastics in a heated state are advanced under positive pressure, saidorifice including a chamber, inner and outer annular lubricating ringsdisposed in spaced concentric order within said chamber, each of saidrings being formed from a metal having a porosity admitting of thepassage of a lubricant under pressure therethrough, each of said ringshaving a tapered body, whereby the wall thickness of the bodyprogressively varies from its plastic-receiving to itsplasticdischarging end.

4. Apparatus for extruding organic plastic materials comprising a diehead having a forming orifice through which plastics in a heated stateare adapted to be advanced under pressure, a lubricating ring positionedin said chamber, said ring having an inner bore of uniform diameterthroughout its length and which bore forms a part of the total length ofsaid orifice, the outer surface of said ring having a frusto-conicalconfiguration to cause the ring to possess a progressively increasingcross-sectional thickness from one end thereof to the other, thethickness of the ring being at its minimum where the plastic materialsenter the ring and at its maximum where said materials leave the ring,and means for introducing a lubricant under pressure into the spaceformed between the outer surfaces of said ring and the bounding wallsurfaces of said chamber.

5. Apparatus for extruding organic plastic materials comprising a diehead having a forming orifice through which plastics in a heated stateare adapted to be advanced under pressure, a lubricating ring positionedin said chamber, said ring having an inner bore of uniform diameterthroughout its length and which bore forms a part of the total length ofsaid orifice, the outer surfaces of said ring possessing a substantiallyspool-shaped configuration, causing said ring to possess progressivelyincreasing body thicknesses from one end thereof to the other, saidthickness being at its minimum value at the material entering end of thering and of maximum value at the material-discharging end of said ring,and means for introducing a lubricant under pressure into the spaceformed between the outer surfaces of said ring and the bounding wallsurfaces of said chamber.

6. Extruding apparatus comprising a sectional head having a body sectionformed with an internal passage to receive and advance plastic materialsdischarged under pressure from an associated extruder; inner,intermediate and outer plate members forming a part of said head; meansseparably uniting said plate members in fixed relative order on saidbody section, with the inner plate member in direct contact with a faceof said body section arranged in registry with the outlet end of thepassage thereof, said inner plate being formed axially with an outwardlyflaring opening, the smaller end of which opening registers with theoutlet end of the body section passage to receive plastic materialdischarged from the latter, said intermediate plate member being formedwith an axial opening arranged in longitudinal registry with the openingof the inner plate member, the opening of said inner plate member beingformed to provide an enlarged oil ring-receiving chamber, said outerplate member being formed with an axial opening disposed in longitudinalregistry with the openings of said inner andintermediate plate members,an oil ring of lubricant-pervious composition positioned in the chamberof said intermediate plate member; and means for supplying a lubricantunder pressure to said chamber for penetration through said ring andinto said opening in the intermediate plate member to facilitate theflow of plastic material through the head.

7. Extruding apparatus as defined in claim 6, and wherein said oil ringis provided with an internal bore registering with the axial openingsformed in said plate members for the transmission of plastic materials,the outer wall surfaces of said ring being tapered in a manner impartingto the ring a progressively increasing wall thickness from the endthereof into which the plastic material enters to the end thereof fromwhich said plastic material is discharged.

DONALD J. WEBER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 445,711 Chase Feb. 3, 18911,858,620 Frandsen May 17, 1932 2,177,633 Blackard Oct. 31, 19392,307,034 Gaenzle Jan. 5, 1943 2,317,689 Larchar Apr. 27, 1943

